1. Field of the Invention
The present invention relates to a premixed combustion burner for a gas turbine. The present invention is devised so that fuel and air can be efficiently premixed to produce fuel gas having a uniform concentration, while achieving reliable prevention of flash back (back fire) by making the flow rate of fuel gas substantially uniform.
2. Description of Related Art
As a premixed combustion burner for a gas turbine, for example, the premixed combustion burner disclosed in Japanese Translation of a PCT International Application, Publication No. 2006-500544 is commonly known.
The invention disclosed in the above patent document is to prevent flash back by lowering the fuel concentration on an inner circumference side (radial direction inner side) of an air passageway.
However, since a total amount of fuel injected into the air passageway per unit time does not change, the fuel concentration in another area (for example, the area on the outer circumference side of the air passageway) increases inversely to the reduction made in the fuel concentration on the inner circumference side of the air passageway, and flame temperature rises on the downstream side, resulting in a possible increase in NOx.